1. Field of the Invention
The present invention relates to optical coupling modules, more particularly to optical coupling modules for coupling alight source with optical fibers for multi-channel optical communication.
2. Description of Related Art
Optical coupling modules are used to optically couple an optical device with optical fibers. Here, the term xe2x80x9coptical devicexe2x80x9d refers not restrictively to a light emitting device (for example, a semiconductor laser), a light receiving device (for example, a photo diode), an optical function component (for example, an electric field absorption type optical modulation module), or the like.
The optical coupling modules disclosed in, for example, the Japanese Patent Application Laid-Open No. H5-88049 and the Japanese Patent Application Laid-Open No. H5-88050 are known.
The optical coupling modules disclosed in the Japanese Laid-Open Patent Application No. H5-88049 contains a lens array constructed by stacking up a pair of micro lens arrays. Each of the micro lens arrays is formed by installing multiple convex lenses that are separated from each other by a prescribed distance. This micro lens array optically couples multiple optical devices with multiple optical fibers.
The optical coupling modules disclosed in the Japanese Laid-Open Patent Application No. H5-88050 contains a substrate on which an aperture unit is formed. Multiple optical fibers are arranged and installed in this aperture unit.
In optically coupling an optical coupling module with optical fibers, the cores of the optical fibers need to be adjusted. An exemplary core adjustment method is described in Kosaka et al., xe2x80x9cSurface Emission Laser Two Dimensional Array Core Unadjusted Packing Push-Pull Type Modulexe2x80x9d, Shingaku Gihou LQE96-144, February 1997. As shown in this reference, it has been conventionally a standard practice to couple a multi-channel optical module with tape fibers via an optical connector. A positioning guide pin is formed in this optical connector.
However, the optical coupling module disclosed in the Japanese Laid-Open Patent Application No. H5-88049 requires an accurate core adjustment operation so as to match the optical axes of the micro lens array with the optical axes of the optical device. In order to tightly seal the optical device using the technique disclosed in the Japanese Laid-Open Patent Application No. H5-88050, the optical coupling module needs to be of a pig tail type. Unless a separate airtight window is installed between the optical fibers and the optical device, a receptacle type optical coupling module connectable to a connector cannot be realized.
Furthermore, in order to use the method disclosed in xe2x80x9cSurface Emission Laser Two Dimensional Array Core Unadjusted Packing Push-Pull Type Modulexe2x80x9d by Kosaka and others, Shingaku Gihou LQE96-144, a high degree of alignment precision is required in aligning the optical device with the guide pin.
Given these problems, it is an object of the present invention to provide an optical coupling module having a high optical coupling efficiency, in which core adjustment operations can be easily performed on its fiber plate and micro lens array and the like.
It is another object of the present invention to provide an optical coupling module having a high optical coupling efficiency, in which optical fibers can be connected to a connector while tightly sealing the optical device.
According to the first aspect of this invention, the optical coupling module has an optical device fixed on a surface of a substrate and a fiber plate which propagates light that enters into the optical device or light that is emitted from the optical device. The fiber plate has multiple bundled optical fibers that are arranged in parallel with optical axes of the optical device.
According to another aspect of this invention, the optical coupling module has a light receiving device and a light emitting device that are fixed on the surface of the substrate and a lens array. This lens array propagates both light that enters into the light receiving device and light emitted from the light emitting device. The lens array aligns the optical axis of the incident light beams parallel with the optical axes of the emitted light beams in a region on an opposite side of the light receiving device or the light emitting device across the lens array by deflecting the incident light or emitted light.
According to still another aspect of this invention, the optical coupling module has an optical device fixed on the surface of the substrate and an image fiber which propagates light that enter into the optical device or lights that are emitted from the optical device. The image fiber has multiple bundled optical fibers that are arranged parallel to the optical axes of the optical device. In this aspect, the optical module is connected to an optical connector. This optical connector has a tape fiber having optical fiber wires that are installed parallel to the optical axes of the optical device corresponding to the light beams that enter into or are emitted from the optical device.
In the following embodiments, the image fiber is coupled with the tape fiber using a split sleeve. Moreover, a positioning guide pin is installed in the optical coupling module and the optical connector.